The Hal Higdon program has a great schedule!

• http://www.halhigdon.com/marathon/Mar00index.htm
   
• http://www.marathontraining.com/marathon.html
   
• http://www.runnersworld.com/home/0,1300,1-51-56,00.html
   
• http://walking.about.com/cs/marathontraining/